December, 1909.] the CODUNG MOTH. 77 



stop, still seems a safe one, and to spray until there are i)U(ldles 

 nnder the tree is merely- a waste of labor and material under New 

 England conditions. There can be no question, however, that 

 spraying with a high pressure either with a barrel or power 

 sprayer makes it possible to drive the spray into all parts of the 

 tree and thoroughly covering the foliage, and hitting the blos- 

 soms opening inward on the far side of the tree, and will give 

 much better results than a low pressure, even if it does not pene- 

 trate the lower calyx cavity. 



5. How the Spray Kills the Larva. Various expedients were 

 used to determine just how the larvae are killed by the spray. 

 If the first spraying kills them principally in the calyx cavity, 

 then a spray applied to the calyces without toucliing the foliage 

 should give nearly as good results and prove that the worms are 

 killed in the calyx cavities. To determine this, several trees 

 were sprayed by hand with nasal atomizers so that the spray was 

 deposited in the calyx of each apple, but practically none was 

 placed on' the foliage. Eleven trees in three plots were thus 

 treated and showed an average benefit of 75 per cent, as com- 

 pared with an average of 82 per cent, where the first spraying 

 alone was applied in the usual way. This proves definitely that 

 most of the lar\'ae killed may be killed in the calyx and that a 

 certain portion are killed by the poison placed on the foliage by 

 the first spraying. 



It has already been shown that by spraying when the eggs are 

 hatching, about Jul}' 1, 70 per cent, of the worminess may be pre- 

 vented. It is possible that the young larvse may be poisoned by 

 this spraying either by eating the foliage or by eating the pois- 

 oned surface of the apple when they enter it. 



If the effect of the spray be due to the poison on the foliage 

 only, then if the apples were covered and the foliage of the 

 tree then sprayed there should be as much benefit as if the apples 

 had been sprayed also. But if there is less benefit with the 

 apples covered, it is evident that the difference in the benefit 

 must represent the value of the spray deposited on the apples. 

 Such an experiment was made twice. In 1907 one tree was 

 sprayed when the eggs were hatching, after all of the apples had 

 been covered with paper bags, which were removed immediately 

 after the spraying. Care was taken to cover only the stems and 

 not the nearby foliage. The vast amount of labor involved in 



